Apparatus for manufacturing spindle components

ABSTRACT

With reference to FIG.  3  the present invention relates to a method of manufacture of a product from a first component ( 4 ) of deformable material and a second component ( 5 ), the method comprising the steps of: 
     inserting a portion of the first component ( 4 ) through an aperture predefined in the second component ( 5 ); and subsequently 
     deforming the material of the first component ( 4 ) to form a pair of spaced apart shoulders ( 50 ) integral with the first component ( 4 ), the spaced apart shoulders ( 50 ) holding therebetween the second component ( 5 ) and thereby preventing the second component ( 5 ) sliding along the first component ( 4 ); wherein: 
     each shoulder ( 50 ) is formed by applying tool means ( 20, 21 ) to a surface of the first component ( 4 ) to create a recess in the surface and to form the shoulder ( 50 ) adjacent to the recess with the shoulder ( 50 ) being formed by displacement of the deformable material of the first component ( 4 ) during the creation of the recess. 
     The present invention also relates to apparatus for performing the method.

This is a Divisional Application of application Ser. No. 09/375,885,filed Aug. 17, 1999, now U.S. Pat. No. 6,427,311, which in turn claimspriority under 35 USC §119 on United Kingdom patent application9822935.4, filed Oct. 20, 1998. Priority on U.S. application Ser. No.09/375,885 and on United Kingdom application 9822935.4 is herebyclaimed.

The present invention relates to apparatus for and a method ofmanufacturing spindles and in particular to a method of rigidly fixingsecondary components such as flanges to a spindle.

Spindles in the form of cylindrical elongated rods are widely used inmechanical devices. Spindles may be used to transmit both axial androtational forces between components of a machine and it is known toprovide secondary components such as keys, keyways, splines and flangeson the spindle to facilitate such force transmission. Spindles may alsocomprise threaded portions and/or undercuts to facilitate attachment ofthe spindle to other components and reaction points such as the chassisin a vehicle. An example of the use of a spindle is as a mounting for aspring means in a vehicle seat adjuster. The spindle is provided with aflange at a point along its longitudinal axis against which one end ofthe spring means abuts. Axial force is transmitted from the spring meansto the spindle (and then onto either a further component or a reactionpoint) through the flange. As can be readily appreciated the jointbetween the flange and the spindle undergoes shear stresses commensuratewith the axial force imparted to the spring means.

It is known to attach secondary components such as keys and flanges tothe central spindle by means of welding or soldering. However, solderingcan result in a joint between the secondary component and the spindlewhich is too weak to transmit the required forces. Welding, whilstproviding a strong joint requires aggressive heating of the componentswhich can be deleterious to the strength and hardness properties of thespindle and/or flange. Soldering and welding can also result in anunacceptably uneven surface to the secondary component and spindle inthe vicinity of the joint and are processes which are labour intensive,slow and expensive to carry out.

The present invention provides in a first aspect a method of manufactureof a product from a first component of deformable material and a secondcomponent, the method comprising the steps of:

inserting a portion of the first component through an aperturepredefined in the second component; and subsequently

deforming the material of the first component to form a pair of spacedapart shoulders integral with the first component, the spaced apartshoulders holding therebetween the second component and therebypreventing the second component sliding along the first component;wherein:

each shoulder is formed by applying tool means to a surface of the firstcomponent to create a recess in the surface and to form the shoulderadjacent to the recess with the shoulder being formed by displacement ofthe deformable material of the first component during the creation ofthe recess.

The present invention provides in a second aspect apparatus for fixedlylocating of a first component having a cylindrical portion a secondcomponent having an aperture therein of a diameter chosen such that thesecond component is mountable on, and freely slidable along thecylindrical portion of the first component, the apparatus comprising:freely rotating means for supporting the first component;

first and second shafts disposed parallel to one another, at least oneof the first and second shafts being movable in a plane perpendicular toits axis in a direction towards the other shaft;

means for rotating the first and second shafts;

first and second roller means axially spaced apart positioned on eachshaft, the first and second roller means each having first and secondinclined surfaces of differing inclinations and the first and secondinclined surfaces of the first roller means on one shaft havinginclinations which match the inclinations of the first and secondinclined surfaces of the first roller means on the other shaft and thefirst and second inclined surfaces of the second roller means on oneshaft having inclinations which match the inclinations of the first andsecond inclined surfaces of the second roller means on the other shaft;wherein:

the first and second shafts are moved towards each other to engage thefirst and second roller means of each shaft with the first component,with the engagement of the roller means with the first componentgenerating forces which act to force the first and second roller meanstowards each other, such force arising due to the differing inclinationsbetween the first and second inclined surfaces of each roller means; andthe engagement of the roller means with the first component can deformmaterial of the first component on either side of the second componentwith the forces applied to the first component forming thereon raisedshoulders, the raised shoulders being located on both sides of thesecond component and fixedly locating second component on the firstcomponent.

The present invention provides apparatus for use in an automatic methodfor fixing secondary components, such as flanges, to spindles withoutsoldering or welding which results in a joint strong enough to transmithigh axial and rotational forces between the spindle and secondarycomponent and yet does not require external or aggressive heating of thespindle and/or secondary component.

The present invention provides a quicker, safer, stronger and moreprecise method of jointing secondary components to spindles than isknown in the state of the art.

Preferred embodiments of the present invention will now be described byway of example only with reference to and as shown in the accompanyingdrawings, in which:

FIG. 1 a front elevation of an apparatus according to a first embodimentof the present invention;

FIG. 2 is a cross-sectional elevation taken on line A—A of FIG. 1;

FIG. 3 is a schematic cross-section of a part of the apparatus of FIG. 1in use;

FIG. 4 is schematic diagram of a part of the apparatus of FIG. 1;

FIG. 5 is front elevation of an apparatus according to a secondembodiment of the present invention;

FIG. 6 is a cross-sectional elevation taken on line B—B of FIG. 5; and

FIG. 7 is cross-sectional side elevation of a further part of theapparatus of FIGS. 1 and 5.

FIGS. 1 and 2 show a first embodiment of an apparatus according to thepresent invention. The apparatus 1 comprises two rotating shafts 3disposed parallel to one another. One of the shafts 3 is on fixedcentres whilst the other shaft is positioned within a hydraulicallyoperated slide (not shown) which allows the shaft 3 to undergocontrolled movement in a direction perpendicular to the axis of theshaft 3 towards the fixed shaft, whilst remaining disposed parallelthereto.

Each shaft 3 comprises an annular roller mount 14 disposed around theshaft 3. A key 15 formed on the shaft 3 and keyway 16 formed in theroller mount 14 transmit rotational forces between the shaft 3 androller mount 14 and ensure that no relative movement occurstherebetween.

The roller mount 14 of each shaft 3 comprises on an outer face 17 tworollers 20, 21 of generally annular shape. The rollers 20, 21 are spacedapart in the axial direction to produce a gap 22 between inner sidefaces 23 of the rollers 20, 21. Positioned within the gap 22 is anannular inner plate 12 which is fixed radially relative to shaft 3. Eachroller 20, 21 is mounted within the roller mount 14 such that it isslidable in the axial direction. The inner side face 23 of each roller20, 21 includes a recess 26 in opposition to one another. Spring means13 in form of Belleville washers or die type springs are anchored ineach recess 26 and span between the two rollers 20, 21 to bias therollers 20, 21 apart such that the gap 22 is maximised when theapparatus is in an inoperative condition. The maximum dimension of thegap 22 is adjustable using adjuster nut 31 and this enables the axialstarting position of the rollers 20, 21 to be established. Differentnumbers and types of Belleville washers may be utilised to alter theeffective spring force between the two rollers 20, 21. The annular innerplate 12 provides a limit stop to prevent the rollers 20, 21 from movingtoo close to one another axially to damage the biasing means 13.

An outer face of the annular rollers 20, 21 forms a rolling face 25. Theconfiguration of the rolling face 25 is most clearly shown in FIGS. 3and 4. Each roller 20, 21 has portions which gradually inclineoutwardly. The rollers 20, 21 also have annular projections 27A and 27Beach of generally triangular shape when viewed in cross-section as shownin FIG. 4. The projections 27A and 27B have relatively steeply inclinedface 28A and 28B (at an α angle to the radial direction) nearest theinner side face 23 of the roller and a shallower inclined face 29A and29B (at an angle β to the longitudinal axis) furthest from the innerside face 23 of the roller. In the preferred embodiment shown in FIGS. 3and 4 α is 45° and β is 9°. In addition the faces 25 have portions 30 ofminimal inclination (at an angle γ to the longitudinal axis and in thepreferred embodiment γ is 1°). The remainder of the faces 25 are rightcylindrical, having a substantially uniform outer diameter.

The component to be machined is a spindle 4 of elongated, generallycylindrical form. The spindle 4 may comprise recessed and/or raisedportions. However the portion of the spindle 4 in the vicinity of thearea to be machined is cylindrical, having an even outer diameter.Preferably the spindle 4 has an elongation of greater than or equal to12 percent.

In the preferred embodiment the component to be fixed to the spindle 4is a washer 5 which has a central aperture of diameter marginallygreater than the outer diameter of the cylindrical portion of thespindle 4 such that the washer 5 is free to slide along the axis of thespindle 4 before being fixed thereto. The outer diameter of the washer 5is immaterial to the present invention.

In use the spindle 4 is positioned between the two shafts 3 such thatthe three longitudinal axes of the two shafts 3 and the spindle 4 arecomponent-linear.

The spindle 4 is supported on a freely rotating rest 40 as shown in FIG.7. The freely rotating rest 40 comprises a series of rolling bearings 41in a generally U-shaped trough in which the spindle 4 may be positionedsuch that the roller bearings bear at a number of points along thelongitudinal length of the spindle 4. The roller bearings 41 help toprevent the axis of the spindle 4 being deformed out of true during themachining process. The freely rotating rest 40 also includes a freelyrotating end stop 43 at one end against which one end of the spindle 4abuts in use. The freely rotating rest 40 and end stop 43 both have theability to rotate freely in order to accommodate the tangential forcesset up by rolling friction and the combined Polar Moment of Inertia whenthe spindle 4 and washer 5 come into contact with the rollers 20, 21.The rotating end stop 43 is movable in the direction of the longitudinalaxis of the spindle 4 form a rearwardly extended position (in which thespindle 4 may be introduced and removed from the apparatus) to aforwardly extended position.

The washer 5 to be fixed to the spindle 4 is introduced into theapparatus and positioned and held between the freely rotating rest 40and the inner plates 12 of the roller mounts 14. The washer 5 is alsopositioned axially-on the spindle 4 such that the washer is disposedbetween the inner side faces 23 of the rollers 20, 21.

The hydraulically operated slide on the movable shaft 3 is operated tobring the two shafts 3 and pairs of rollers 20, 21 towards one anothercausing the rolling faces 25 of each roller 20, 21 to contact thesurface of the spindle 4. The movement of the movable shaft 3 on thehydraulic slide is preferably controlled by automated means such ascomputerised control system of known design.

The pair of rollers 20 contact the spindle 4 axially to one side of thewasher 5 and the other pair of rollers 21 contact the spindle 4 axiallyon the other side. Due to the low frictional characteristics of thefreely rotating roller rest 40 and rotating end stop 41, contact betweenthe rollers 20, 21 and spindle 4 causes the spindle 4 to rotate suchthat there is no relative tangential movement between the rolling faces25 and the spindle surface 4 at the junction. In other words the rollers20, 21 positively rotate the spindle 4 without slippage between thespindle 4 and rolling faces 25.

Due to its enlarged diameter compared to the remainder of the roller,the extremity of the projection 27 is the first portion of the rollingfaces 25 of the rollers 20, 21 to contact the spindle surface. Contactof the projection 27 with the spindle 4 results in a force being appliedto the spindle 4. Due to the steeply inclined 28 and shallowly inclined29 faces of the projection 27, on initial penetration of the projection27 into the spindle surface the radial force supplied by the hydraulicslide moving the movable shaft 3 creates a force between each inclinedface 28, 29 and the spindle 4 with radial and longitudinal components.Due to difference in angles α and β there is set up a differential forcein the longitudinal direction from each projection 27 in the directionof the washer 5. This differential force causes the rollers 20, 21 tomove towards each other and the washer 5 against the biasing force ofthe Belleville springs 13 as the shafts 3 are brought into closerproximity. Due to the symmetry of the rollers 20, 21 about the plane ofthe washer 5 the locus of movement of each of the rollers 20, 21 mirrorone another. Thus the action of the projection 27 of the rollers 20, 21deforms the material of the spindle in the vicinity of the washer 5 bothradially and longitudinally to form an identical raised shoulder 50 oneither side of the washer 5. The raised shoulder 50 has a diametergreater than that of both the remainder of the cylindrical portion ofthe spindle and the diameter of the aperture of the washer 5. Thelongitudinal deformation of the material of the spindle is such that theraised shoulder 50 also abuts against the side faces of the washer 5.Thus the raised shoulder firmly fixes the longitudinal position of thewasher 5 relative to the spindle 4. The deformation can also be greatenough to rotationally fix the washer 5 relative to spindle 4. Theintegrity of the rotational fixation of the washer 5 may be improved byproviding surface indentations or serrations in the side faces of thewasher near the aperture edge into which deformed material may flow; thedeformed material and indentations having a keying effect.

The size of the projection 27 is such that the total volume of materialdeformed is slightly greater than the volume of material raised abovethe initial diameter of the cylindrical portion of the spindle necessaryto form the raised shoulder. The small excess of material deformedcreates a cusp 51 of material adjacent to the side faces of the washer5. The cusps so formed prevent the inside side faces 23 of the rollers20, 21 contacting and damaging the side faces of the washer 5.

The angles α and β may be altered in order to created different profilesof raised shoulder and also to alter the magnitude of the differentialforce. The greater the difference between angles α and β the greater thedifferential force. It has been found that angle α is preferably atleast four times the magnitude of the angle β to create a sufficientdifferential force. In the embodiment described above angle α equals 45°and angle β equals 9°.

The minimally inclined parts of surfaces 30 of the roller 20, 21 spacesthe remainder of the rolling faces apart from the spindle surface. Theremainder of the rolling faces advantageously “irons” out anydeformities in the spindle surface remote from the raised shouldercaused by the forming process.

The presence of identical sets of rollers 20, 21 on both shafts 3 meansthat forces applied to the spindle in the forming process aresymmetrical; no bending moments are imparted on the spindle 4 and noresultant axial forces are experienced by the shafts.

After formation of the raised shoulders 50 the movable shaft 3 is movedaway from the fixed shaft causing the rollers 20, 20 to return to thereinoperative, spaced apart position under the bias of the Bellevillewashers 13. The rotating end stop 51 is moved to its rearward mostposition and the finished spindle 4 is removed leaving the apparatusready to receive the next spindle to be formed.

The present invention is suitable for precisely positioning thelongitudinal placement of the washer 5 on the spindle 4 since thelongitudinal position of the washer 5 is determined solely by thedistance between the rotating end stop 43 against which one end of thespindle abuts and the centre of the gap 22 between the two rollers 20,21. This distance is consistent and maybe easily calibrated.

A second embodiment of the present invention is shown in FIGS. 5 and 6.The rolling faces 25 of the rollers 20, 21 in the second embodiment areas described in the first embodiment. In the embodiment however, themovement of each roller 20, 21 is positively and separately controlledby hydraulic means. Hydraulic pressure and flow is provided to eachshaft 3 through a suitable known connection means such as Deublinrotating distributors. Hydraulic flow is fed to first and second pistonmeans 61, 62 through internal conduits 63, 64. Each piston means 61, 62comprises a piston 65 fixedly attached to a roller carrier 66. Eachroller carrier 66 is attached to, and moves with one of the rollers 20,21. Thus the piston means 61, 62 is utilised to move the roller 20, 21inwardly towards each other and are biased outwardly by springs such asspring 100 or such as the Belleville Springs 13 of the first embodiment.Adjuster nuts 101 establish the axial starting position of the rollers20, 21 which has to be precise relative to the geometry of thecomponents and the volume of the shoulders 50 to be rolled. As aconsequence of the use of the piston means 61, 62 each roller 20, 21 maybe moved independently of the other.

Each roller 20, 21 is of the same general external configuration as inthe first embodiment and an annular inner plate 12 is again provided inthe gap 22 between the rollers 20, 21 as a compression limit stop.During the forming process the washer 5 rests against the rollers 20, 21and must not contact the inner plate 12.

A digital control system of known type controls movement of each piston65 and the hydraulic slide of the moveable shaft 3.

The piston 65 of the first piston means 61 has a slightly greater pistonarea than the piston 65 of the second piston means 62. In one aspect ofthe present invention the first piston means 61 has a piston area 2%greater than that of the second piston means 62. Due to identicalhydraulic pressure being fed to each piston means, the increased area ofthe first piston means that a marginally greater force is applied to thespindle 4 by the first piston means 61 than by the second piston means62. This has the effect of ensuring that the spindle is at all timesabutted firmly against the rotating end stop 43 since the first pistonmeans acts towards the rotating end stop 43.

The first piston means 61 and corresponding roller 20 are movedlongitudinally under control of the control system such that theprojection 27A moves from position A1 in FIG. 3 to position A2. Movementof the first piston means 61 is limited by shoulder 70 against which theroller carrier abuts. Precise longitudinal positioning of the washer 5on the spindle 4 may thus be ensured by calibrating the distance betweenthe freely rotating end stop 43 and the shoulder 70. The second pistonmeans 62 and roller 21 are operated to move the corresponding projection27B from position B1 to position B2 as shown in FIG. 3. Different forcesarise because of the different piston areas and therefore the secondpiston means 62 reaches its limit of motion after the first piston means61. Advantageously the hydraulic system is used to supplement thedifferential forces set up by the geometry of the projection 27 toprovide an improved forming process.

The hydraulic system used with the second embodiment comprises twoindependent power sources, controlled by electrically operated servovalves for each shaft 3. The servo valves are controlled by a closedloop electronic amplifier and digital position system. The piston meansare provided with a feedback system working off a volumetric analysergiving square wave output signals which correspond to the hydraulic flowrate to each shaft. In this way the control system can ensure that thecorresponding rollers 20, 21 on each shaft 3 move in precise alignmentso as to avoid imparting any twisting forces on the spindle and/orvibrations to the apparatus. A feedback system on the main hydraulicslide, having a digital encoder with a reference pulse, is used tocomponent-ordinate the timing of the piston means with the movable shaft3.

The two independent axis controls are linked for relative timing by thereference pulse. The velocity and stroke imparted to the forming rollers20, 21 ensures a locus of travel along angle β for each of the rollers20, 21 until the final form position A2, B2 is reached.

The present invention according to the second embodiment has theadvantage of the application of controllable forces, timing and geometryto enable the rollers 20, 21 to be designed to create a raised shoulder50 of any required shear section and diameter. For example, theapplicants have produced a spindle 4 having a thrust washer 5 with ashear section of ≦1.80 mm per side which gives ≦20 Kn of shear strength.The performance of the two pairs of rollers 20, 21 where constructionand operation accuracy ensure close control of concentricity and axialaccuracy of the rollers 20, 21 (≦0.03 per roller at 170 Dia) buildsinherent accuracy into the rolling process. Ongoing SPC data showscapability at ≦0.02 axial runout at 18 Dia on the washer 5 relative tothe diameter of the spindle 4 adjacent to the washer 5.

Whilst the present invention has been described with reference tojoining an annular washer to a spindle the invention is not limited tosuch. For example the apparatus and method described above may also beadapted for joining non-circular symmetric components to spindles havingat least a cylindrical portion.

What is claimed is:
 1. Apparatus for fixedly locating on a firstcomponent having a cylindrical portion a second component having anaperture therein of a diameter chosen such that the second component ismountable on, and freely slidable along the cylindrical portion of thefirst component, and apparatus comprising: freely rotating means forsupporting the first component; first and second shafts disposedparallel to one another, at least one of the first and second shaftsbeing movable in plane perpendicular to its axis in a direction towardsthe other shaft; means for rotating the first and second shafts; firstand second roller means axially spaced apart positioned on each shaft,the first and second roller means each having first and second inclinedsurfaces of differing inclinations and the first and second inclinedsurfaces of the first roller means on one shaft having inclinationswhich match the inclinations of the first and second inclined surfacesof the first roller means on the other shaft and the first and secondinclined surfaces of the second roller means on one shaft havinginclinations which match the inclinations of the first and secondinclined surfaces of the second roller means on the other shaft;wherein: the first and second shafts can be moved towards each other toengage the first and second roller means of each shaft with the firstcomponent, with the engagement of the roller means with the firstcomponent generating forces which act to force the first and secondroller means towards each other, such forces arising due to thediffering inclinations between the first and second inclined surfaces ofeach roller means; and the engagement of the roller means with the firstcomponent can deform material of the first component on either side ofthe second component with the forces applied to the first componentforming thereon raised shoulders, the raised shoulder being located onboth sides of the second component and fixedly locating the secondcomponent on the first component.
 2. Apparatus as claimed in claim 1wherein the first and second inclined surfaces of each roller meanstogether define on the roller means an annular region of triangularcross-section.
 3. Apparatus as claimed in claim 1 wherein each of thefirst and second shafts comprises identical first and second rollermeans movable in unison on engagement with the first component so thatno bending moments are imposed on the first component.
 4. Apparatus asclaimed in claim 1, wherein the roller means each have first and secondinclined surfaces configured such that the total volume of material ofthe first component deformed is greater than the volume of materialraised above the diameter of the cylindrical portion of the firstcomponent necessary to form the shoulders such that the excess deformedmaterial forms cusps of material adjacent to the side of the secondcomponent.
 5. Apparatus as claimed in claim 1, wherein the firstinclined surface of each rolling means is relatively steeply inclinedand the second inclined surface of each rolling means is relativelyshallowly inclined.
 6. Apparatus as claimed in claim 1, wherein thefirst inclined surface of each roller means is inclined at approximately45° to the longitudinal axis.
 7. Apparatus as claimed in claim 1 whereinthe second inclined surface is inclined at approximately 9° thelongitudinal axis.
 8. Apparatus a claimed in claim 1 wherein the rollingmeans further comprises a portion of minimal inclination and a portionof even diameter.
 9. Apparatus as claimed in claim 1 wherein the firstand second roller means are biased apart from one another in aninoperative state.
 10. Apparatus as claimed in claim 9 wherein thebiased force is created by a spring means comprising a plurality ofBelleville washers.
 11. Apparatus as claimed in claim 1 wherein thefirst and second roller means are connected to respective first andsecond piston means.
 12. Apparatus as claimed in claim 11 comprisinghydraulic actuation means for hydraulically actuating the first andsecond piston means.
 13. Apparatus as claimed in claim 12 wherein thefirst piston means has a greater piston area than the second pistonmeans and both piston means receive hydraulic fluid from a common sourceat a common pressure whereby a greater longitudinal component of forceis applied to the first component in the direction of movement of thefirst piston means than in the direction of the second piston means suchthat the first component is firmly abutted against the rotating endstop.
 14. Apparatus as claimed in claim 13 wherein stop means isprovided to limit the motion of the first piston means and fix the exactposition of the first piston means relative to the rotating end stop.15. Apparatus as claimed in claim 1 wherein the at least one movableshaft is slidable on a hydraulically actuated slide.
 16. Apparatus asclaimed in claim 15 wherein the hydraulic actuation means connected tothe first and second piston means and hydraulic slide includes one ormore servo valves to control movement of the first and second rollers oneach shaft to ensure that each pair of first and second rollers on thetwo shafts move in unison.
 17. Apparatus as claimed in claim 1 whereinthe freely rotating means comprises a substantially U-shaped elongatedcarrying means including a plurality of roller bearings contactable inuse with the first component.
 18. Apparatus as claimed in claim 17wherein the freely rotating support means comprises a rotating end stopagainst which an end of the first component abuts.
 19. Apparatus asclaimed in claim 18 wherein the rotating end stop is movable from aforwardly extended position to a rearwardly extended position. 20.Apparatus as claimed in claim 15 wherein computer controlled means areprovided for controlling actuation of the hydraulically actuated slide.